The use of PST files can be convenient for the end-users, but the truth is that, for the SysAdmins these files can really be a headache. Fortunately there are some registry keys that can be used to prevent the creation of PST files.
Locate the following registry file HKEY_LOCAL_MACHINE\Software\Microsoft\Office\12.0\Outlook\ (12.0 is for Outlook 2007, for Outlook 2003 use 11.0). Under this key create the following registry values:
Value Name: DisablePst
Data Type: REG_DWORD
To remove the Outlook Data File option in Outlook, which is shown under the menu File, locate the registry key HKEY_CURRENT_USER/Software/Policies/Microsoft/Office/12/Outlook/DisableCmdBarItemsList/ and create the following value
Value Name: TCID1
Data Type: REG_SZ
To prevent the AutoArchive option in Outlook, change all these values to 0:
These setting can also be controlled using the Office 2007 ADM Templates.